U.S. patent number 8,312,142 [Application Number 11/068,055] was granted by the patent office on 2012-11-13 for discontinuous transmission/reception in a communications system.
This patent grant is currently assigned to Motorola Mobility LLC. Invention is credited to Mika Rinne, Olav Tirkkonen.
United States Patent |
8,312,142 |
Rinne , et al. |
November 13, 2012 |
Discontinuous transmission/reception in a communications system
Abstract
Allocation information is transmitted in a communications system
for indicating allocation of sets of transmission resources to
communications devices. At least one allocation rule is defined for
associating sequences of sets of transmission resources with
communications devices, and a communications device monitors
allocation information of sets of transmission resources associated
with it. Communications devices are informed of their respective
allocation rules. Transmission resources for the communications
devices are allocated based at least on said allocation rules.
Inventors: |
Rinne; Mika (Espoo,
FI), Tirkkonen; Olav (Helsinki, FI) |
Assignee: |
Motorola Mobility LLC
(Libertyville, IL)
|
Family
ID: |
36933075 |
Appl.
No.: |
11/068,055 |
Filed: |
February 28, 2005 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20060195576 A1 |
Aug 31, 2006 |
|
Current U.S.
Class: |
709/226; 370/252;
709/228; 713/320 |
Current CPC
Class: |
H04W
72/042 (20130101); H04L 47/822 (20130101); H04L
47/70 (20130101); H04L 47/824 (20130101); Y02D
70/24 (20180101); H04W 72/04 (20130101); Y02D
70/25 (20180101); Y02D 30/70 (20200801); Y02D
70/1224 (20180101); H04W 24/00 (20130101); H04W
52/0216 (20130101); Y02D 70/23 (20180101); H04W
52/0219 (20130101); Y02D 70/142 (20180101); Y02D
70/1244 (20180101) |
Current International
Class: |
G06F
15/173 (20060101) |
Field of
Search: |
;709/226-231
;370/230,311,278,335,328,252-253 ;340/7.32-7.34
;455/343.1-343.4,450 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
US. Office Action issued Oct. 18, 2010 in U.S. Appl. No.
11/885,167. cited by other.
|
Primary Examiner: Bengzon; Greg C
Claims
The invention claimed is:
1. A method comprising: transmitting, by a network element,
allocation information for suggesting allocation of sets of
transmission resources; negotiating at least one configurable
allocation rule for associating at least one sequence of sets of
transmission resources with at least one communications device in
an active state to allow discontinuous reception at the at least
one communications device, wherein at least one of said at least
one communications device is configured to monitor allocation
information of sets of transmission resources associated with the
at least one communications device and wherein said at least one
configurable allocation rule defines that a communications device
monitors allocation information at least periodically using a first
period and a second period , which is shorter than the first
period, and conditionally monitors allocation information
periodically using the second period wherein the at least one
configuration allocation rule defines that the second period is
used on one of the following conditions: the allocation information
monitored using the first period does not indicate transmission
resources allocated to the communications device until the
communication device determines transmission resources allocated to
the device, the allocation information monitored using the first
period indicates the start of transmission resources allocated to
the communications device until the allocation information
indicates no more transmission resources allocated to the
communication device, and information carried by transmission
resources associated with the first period is erroneously received
by the communications device wherein the second period is used for
retransmissions until a positive acknowledgement is received; and
allocating transmission resources for said at least one
communications device based at least on said at least one
configurable allocation rule.
2. A method as defined in claim 1, wherein said first period is
defined as one of: a time period and a number of sets of
transmission resources.
3. A method as defined in claim 1, wherein the first period is
based on an expected transmission time interval.
4. A method as defined in claim 1, wherein said at least one
configurable allocation rule defines that a communications device
monitors allocation information of a sequence of sets of
transmission resources starting from a given set of transmission
resources.
5. A method as defined in claim 4, comprising announcing the given
set of transmission resources using an earlier set of transmission
resources.
6. A method as defined in claim 1, wherein said at least one
configurable allocation rule defines that a communications device
monitors allocation information periodically using a first period
and allocation information of a sequence of sets of transmission
resources starting from a given set of transmission resources.
7. A method as defined in claim 1, comprising sending information
relating to allocation rules to said at least one communications
device.
8. A method as defined in claim 1, comprising receiving information
relating to allocation rules from at least one of said at least one
communications device.
9. A method as defined in claim 1, wherein a set of transmission
resources is one of: a frame, a superframe, a slot, a set of
symbols of a frame.
10. A method as defined in claim 1, comps transmitting allocation
information associated with a set of transmission resources with
the set of transmission resources.
11. A method as defined in claim 1, wherein allocation information
associated with a set of transmission resources indicates
allocation of transmission resources in at least one direction of:
downlink and uplink.
12. A method as defined in claim 1, wherein a set of transmission
resources is a piece of information on a shared medium and
allocation information associated with a piece of information is
transmitted with the piece of information.
13. A method as defined in claim 1, where allocation information of
a set of transmission resources comprises at least one identifier
associated with a communications device.
14. A method as defined in claim 13, wherein the at least one
identifier is associated with a radio link relating to the
communications device.
15. A method as defined in claim 1, wherein allocation information
of a set of transmission resources comprises at least one
identifier associated with at least one of: a communications
device, a group of communications devices.
16. A method as defined in claim 1, comprising assigning to a group
of communications devices an identifier associated with the
group.
17. A method as defined in claim 1, comprising defining allocation
rules for a plurality of communications devices so that the
plurality of communications devices monitor the same sets of
transmission resources.
18. A method as defined in claim 17, comprising defining a first
plurality and a second plurality, the first plurality monitoring a
first sequence of sets of transmission resources and the second
plurality monitoring a second sequence of sets of transmission
resources.
19. A method as defined in claim 1, comprising adjusting said at
least one configurable allocation rule depending on at least one
of: transmission load, changing allocation needs, traffic type,
traffic flows, device capability, bit rate requirements, delay
requirements, buffering requirements.
20. An apparatus comprising: at least one processor; and at least
one memory including computer program code, the at least one memory
and the computer program code configured to, with the at least one
processor, cause the apparatus at least to negotiate at least one
configurable allocation rule to associate at least one sequence of
sets of transmission resources with at least one communications
device in an active state to allow discontinuous reception at the
at least one communications device, wherein at least one of said at
least one communications device is configured to monitor allocation
information of sets of transmission resources associated with the
at least one communications device and wherein said at least one
configurable allocation rule defines that a communications device
monitors allocation information at least periodically using a first
period and a second period , which is shorter than the first
period, and conditionally monitors allocation information
periodically using the second period wherein the at least one
configuration allocation rule defines that the second period is
used on one of the following conditions: the allocation information
monitored using the first period does not indicate transmission
resources allocated to the communications device until the
communication device determines transmission resources allocated to
the device, the allocation information monitored using the first
period indicates the start of transmission resources allocated to
the communications device until the allocation information
indicates no more transmission resources allocated to the
communication device, and information carried by transmission
resources associated with the first period is erroneously received
by the communications device wherein the second period is used for
retransmissions until a positive acknowledgement is received, and
allocate transmission resources for said at least one
communications device based at least on said at least one
configurable allocation rule.
21. The apparatus as defined in claim 20, wherein said first period
is defined as one of: a time period and a number of sets of
transmission resources.
22. The apparatus as defined in claim 20, wherein the first period
is based on an expected transmission time interval.
23. The apparatus as defined in claim 20, wherein said at least one
configurable allocation rule is configured to define that a
communications device monitors allocation information of a sequence
of sets of transmission resources starting from a given set of
transmission resources.
24. The apparatus as defined in claim 23, wherein the given set of
transmission resources is announced using an earlier set of
transmission resources.
25. The apparatus as defined in claim 20, wherein said at least one
configurable allocation rule is configured to define that a
communications device monitors allocation information periodically
using a first period and allocation information of a sequence of
sets of transmission resources starting from a given set of
transmission resources.
26. The apparatus as defined in claim 20, wherein the transmitter
is configured to send information relating to allocation rules to
said at least one communications device.
27. The apparatus as defined in claim 20, comprising a receiver
configured to receive information relating to allocation rules from
at least one of said at least one communications device.
28. The apparatus as defined in claim 20, wherein a set of
transmission resources is one of: a frame, a superframe, a slot, a
set of symbols of a frame.
29. The apparatus as defined in claim 20, wherein the transmitter
is configured to transmit allocation information associated with a
set of transmission resources with the set of transmission
resources.
30. The apparatus as defined in claim 20, wherein allocation
information associated with a set of transmission resources is
configured to indicate allocation of transmission resources in at
least one direction of: downlink and uplink.
31. The apparatus as defined in claim 20, wherein a set of
transmission resources is a piece of information on a shared medium
and allocation information associated with a piece of information
is transmitted with the piece of information.
32. The apparatus as defined in claim 20, wherein allocation
information of a set of transmission resources comprises at least
one identifier associated with a communications device.
33. The apparatus as defined in claim 32, wherein the at least one
identifier is associated with a radio link relating to the
communications device.
34. The apparatus as defined in claim 20, wherein allocation
information of a set of transmission resources comprises at least
one identifier associated with at least one of: a communications
device, a group of communications devices.
35. The apparatus as defined in claim 20, wherein an identifier
associated with a group of communications devices is assigned to
the group.
36. The apparatus as defined in claim 20, wherein the processor is
configured to define allocation rules for a plurality of
communications devices so that the plurality of communications
devices monitor the same sets of transmission resources.
37. The apparatus as defined in claim 36, wherein the processor is
configured to define a first plurality and a second plurality, the
first plurality configured to monitor a first sequence of sets of
transmission resources and the second plurality configured to
monitor a second sequence of sets of transmission resources.
38. The apparatus as defined in claim 20, wherein said at least one
configurable allocation rule is adjusted depending on at least one
of: transmission load, changing allocation needs, traffic type,
traffic flows, device capability, bit rate requirements, delay
requirements, buffering requirements.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to transmission of data in a
communications system. In particular the present invention relates
to discontinuous transmission/reception of data in a communications
system.
2. Description of the Related Art
A communication system can be seen as a facility that enables
communication sessions between two or more entities such as user
equipment and/or other nodes associated with the communication
system. The communication may comprise, for example, communication
of voice, data, multimedia and so on. Communication systems
providing wireless communication for user equipment are known.
Cellular communication systems are configured to have a cell
structure, and typically they support communication with user
equipment changing locations (mobile users). The support for
communications for mobile users may include support for handing
existing connections from one cell to another cell. At least
routing of calls or communications for a mobile user in a new cell
is typically supported in cellular systems. Some examples of a
cellular system are the Global System for Mobile Telecommunications
(GSM) and General Packet Radio Service (GPRS). GPRS provides
packet-switched data services and utilizes the infrastructure of a
GSM system. Further examples of a cellular system are third
generation telecommunication systems, which support both
packet-switched and circuit-switched transfer. The Wideband Code
Division Multiple Access (WCDMA) system is one example of a third
generation cellular telecommunication system.
Traditionally communications systems have been circuit-switched
systems, where a certain amount of resources is reserved for a
connection/call continuously irrespective of the need of
transmitting data at a particular moment in time. The reserved
amount of resources may be, for example, a dedicated channel. The
channel, in turn, may be defined for example by a certain slot in
successive time frames in a time division multiplex system, a
certain frequency in a frequency division multiplex system or a
certain channelization code in a code division multiplex
system.
In this allocation scheme, resources that are announced to a given
communications device are occupied and are not available to any
other communications devices, before the allocation is released.
The resource occupation is maintained, even if the given
communications device has actually no data to transmit or to
receive. For allocating transmission resources in a more efficient
way, it is possible to take into account the actual need for
transmission capacity when allocating transmission resources. For
time-critical data (for example, a voice call) resources may be
allocated on a continuous basis, but less time critical data may be
buffered until there are free transmission resources. In the novel
communication systems the available bandwidth and symbol rate is
huge compared to the traditional ones. Thus, any fixed reservation
of resources, which are actually not in use, will cause unnecessary
loss of efficiency.
In novel communication systems, due to their inherent large
transmission capacity, it is possible to share the communication
medium efficiently among many communications devices. The
communications devices typically monitor the shared medium for
transmitting and receiving information most efficiently. The
communications systems work by random access and collision
detection or alternatively the allocation of resources is given in
an explicit way by signalling.
When transmitting information on a shared medium, the
communications devices typically need to know exactly which pieces
of information are intended for them to receive and which pieces of
transmission resources are intended for them to transmit. This is
typically done by exchanging explicit allocation information
between the communications system and the communications devices.
The allocation information may be transmitted on a shared
signalling channel or using an associated signalling channel. High
Speed Downlink Packet Access in the WCDMA system, for example, uses
a high-capacity shared data channel for downlink data transfer and
a low-capacity shared signalling channel for informing the
communications devices about the specific resource allocations on
the shared data channel. In a Wireless Local Area Network, each
data packet header contains identifiers of the communications
device to indicate which device this data packet is addressed to
and which device needs to decode it. Thus, all communications
devices need to monitor and process the headers of all data packets
for being able to receive data addressed to it.
When a communications device is listening to a shared medium, it
needs to monitor allocation information continuously or at least
very frequently for every transmission unit for determining whether
it should receive data in the downlink direction or whether it
could transmit data in the uplink direction. Thus allocation
information needs to be monitored continuously at least once per
transmission unit, although the actual data transmission and/or
reception occurs in a discontinuous manner. Continuous monitoring
and decoding of potential presence of allocation information
consumes power. Especially for wireless communications devices,
power consumption is a critical factor.
Embodiments of this invention aim to provide an efficient solution
for discontinuous transmission and/or reception.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, there is
provided a method for allocating resources in a communication
system to at least one communications device, the method
comprising
transmitting allocation information for indicating allocation of
sets of transmission resources,
defining at least one allocation rule for associating at least one
sequence of sets of transmission resources with at least one
communications device, a communications device monitoring
allocation information of sets of transmission resources associated
with the communications device,
informing said at least one communications device of said at least
one allocation rule, and
allocating transmission resources for said at least one
communications device based at least on said at least one
allocation rule.
In accordance with a second aspect of the invention, there is
provided a method of operating a communications device, the method
comprising
determining at least one allocation rule for the communications
device, said at least one allocation rule defining a sequence of
sets of transmission resources associated with the communications
device,
monitoring allocation information of said sequence of sets of
transmission resources, and
determining whether said sequence of sets of transmission resources
contains transmission resources allocated for the communications
device based on the allocation information of said sequence of sets
of transmission resources.
In accordance with a third aspect of the invention, there is
provided a communication system, configured to
transmit allocation information for indicating allocation of sets
of transmission resources,
define at least one allocation rule for associating at least one
sequence of sets of transmission resources with at least one
communications device, a communications device monitoring
allocation information of sets of transmission resources associated
with the communications device,
inform said at least one communications device of said at least one
allocation rule, and
allocate transmission resources for said at least one
communications device based at least on said at least one
allocation rule.
In accordance with a fourth aspect of the invention, there is
provided a transceiver network element, configured to
transmit allocation information for indicating allocation of sets
of transmission resources,
define at least one allocation rule for associating at least one
sequence of sets of transmission resources with at least one
communications device, a communications device monitoring
allocation information of sets of transmission resources associated
with the communications device,
inform said at least one communications device of said at least one
allocation rule, and
allocate transmission resources for said at least one
communications device based at least on said at least one
allocation rule.
In accordance with a fifth aspect of the invention, there is
provided a communications device, configured to
determine at least one allocation rule for the communications
device, said at least one allocation rule defining sequence of sets
of transmission resources associated with the communications
device,
monitor allocation information of said sequence of sets of
transmission resources, and
determine whether said sequence of sets of transmission resources
contains transmission resources allocated for the communications
device based on the allocation information of said sequence of sets
of transmission resources.
In accordance with a sixth aspect of the invention, there is
provided a computer program comprising instructions for causing a
data processing system comprising at least one data processor to
perform the following steps, when the program is run on the data
processing system:
transmitting allocation information for indicating allocation of
sets of transmission resources,
defining at least one allocation rule for associating at least one
sequence of sets of transmission resources with at least one
communications device, a communications device monitoring
allocation information of sets of transmission resources associated
with the communications device,
informing said at least one communications device of said at least
one allocation rule, and
allocating transmission resources for said at least one
communications device based at least on said at least one
allocation rule.
In accordance with a sixth aspect of the invention, there is
provided a computer program comprising instructions for causing a
data processing system comprising at least one data processor to
perform the following steps, when the program is run on the data
processing system:
determining at least one allocation rule for the communications
device, said at least one allocation rule defining a sequence of
sets of transmission resources associated with the communications
device,
monitoring allocation information of said sequence of sets of
transmission resources, and
determining whether said sequence of sets of transmission resources
contains transmission resources allocated for the communications
device based on the allocation information of said sequence of sets
of transmission resources.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described by way
of example only with reference to the accompanying drawings, in
which:
FIG. 1 shows, as an example, a communications system where
embodiments of the inventions are applicable;
FIG. 2a shows, as an example, a flowchart of a method in accordance
with a first embodiment of the invention;
FIG. 2b shows, as an example, a flowchart of a method of operating
a communications device in accordance with the first embodiment of
the invention;
FIG. 3a shows schematically a first allocation rule example;
FIG. 3b shows schematically a second allocation rule example;
FIG. 3c shows schematically a third allocation rule example;
FIG. 4a shows schematically, as an example, a procedure for
assigning allocation rules for the downlink direction;
FIG. 4b shows schematically, as an example, a procedure for
negotiating allocation rules for the uplink direction;
FIG. 4c shows schematically, as examples, protocol messages for
carrying allocation rule assignment and negotiation
information;
FIG. 5a shows, as an example, allocation of frames for up to eight
active users;
FIG. 5b shows, as an example, allocation of frames for up to
sixteen active users, the users being split to two sets for
efficient monitoring of their allocation information;
FIG. 5c shows, as an example, allocation of frames for up to 32
active users, the users being split to four sets for efficient
monitoring of their allocation information;
FIG. 5d shows, as an example, allocation of frames for 20 active
users, the users being split unequally up to four sets for
efficient monitoring of their allocation information;
FIG. 5e shows a further example of allocation of frames, where the
allocation decoding periods are different for different users;
FIG. 5f shows schematically an example of the use of a group
identifier;
FIG. 6 shows, as an example, allocation for three terminals having
different types of traffic, two terminals having intense short term
allocations and one terminal having rare but regular long term
allocations;
FIG. 7a shows, as an example, structure of a protocol message
announcing start of a next continuum and optionally an allocation
rule in the continuum;
FIG. 7b shows, as an example, frames allocated using a continuum
allocation rule;
FIG. 8a shows Table 1, which is an example of a base station table
for allocations;
FIG. 8b shows Table 2, which is a further example of a base station
table for allocation;
FIG. 8c shows Table 3, which is an example of a terminal table for
allocation relating to Table 2 of the base station;
FIG. 8d shows Table 4, which is a further example of a terminal
table for allocation relating to Table 2 of the base station;
FIG. 8e shows Table 5, which is an example of an allocation table
of a terminal having connections to more than one base station;
FIG. 9a shows schematically idle and active states and transitions
between the states;
FIG. 9b shows a state diagram for the active state DTX/DRX
allocation rules; and
FIG. 9c shows possible triggers for allocation rule updates or for
DTX/DRX rule updates.
DETAILED DESCRIPTION OF EMBODIMENTS
In the following description, discontinuous transmission and/or
reception means that the communication device need not stay active
in decoding information that is not assigned for it, but can pause
for periods of in-activity and can wake-up for periods of activity
in an efficient way. The communication network rarely has this
opportunity, but it plays a significant role to negotiate and
arrange such discontinuous transmission and reception opportunities
for the communication devices.
Embodiments of the invention may be applied in connection with a
communication medium shared among a set of communications devices.
For example, a shared channel in a communications system may use an
embodiment of the invention, where other channels employ different
allocation schemes. As a second example, all information
transmission in a communications system may be designed to operate
in accordance with embodiments of the invention.
FIG. 1 shows, as an example, a communications system 100 where
embodiments of the invention are applicable. The communications
system 100 contains a plurality of transceiver network elements
110a, 110b and 110c. In some communications systems, these
transceiver network elements may be called base stations or access
points. Each base station may contain one or more sectors, each
sector forming a communication cell. The communications system 100
may further contain a controller network element 120 responsible
for controlling transmission resources. As an alternative, the
control functionality may be implemented in a distributed manner in
the transceiver network elements 110. The communication system may
further contain a router 130, responsible for packet-switched
transport functionality. The router 130 typically provides access
to further routers and packet-data networks.
A communications device 101 communicates with the communication
system 100 by receiving information transmitted by one or more than
one transceiver network element 110 and by transmitting information
to the communications system. It is possible that the signal
transmitted by the communications device 101 is received and
processed by one or more transceiver network element 110. It is
also possible that the signal transmitted by a transceiver 110 of a
communications system, is received by one or more communications
device 101.
Embodiments of the invention do not set any specific requirements
on the multiplexing or modulation techniques used in the
communications system 100. The communications system 100 may employ
any suitable combination of multiplex techniques. The term
transmission resources in this description refers to any set of
transmission resources that can be divided between a set of
communications devices. For example, communications devices 101 may
be multiplexed using frequency and/or time and/or code division
techniques. Communications devices may use frequency division, time
division, or code division techniques or any set of their
combinations. Non-orthogonal multiplexing may also be used, where
multiple users share the same orthogonal transmission resource, for
example space-division or dirty paper coding techniques. The
communications system 100 may employ any modulation technique,
including multicarrier modulation, compatible with the multiplexing
techniques used in the communications system 100.
In embodiments of the invention, information is transmitted using a
series of sets of transmission resources. A set of transmission
resources may be, for example, a radio frame, a composition of
frames (a superframe), a set of slots or symbols in a frame, or
data blocks on a shared medium. Allocation of transmission
resources within a set of transmission resources is defined by
allocation information associated with the set of transmission
resources. This allocation information is often referred to as an
allocation table, and allocation information is called
AllocationTable below in connection with the second embodiment.
Allocation information of a set of transmission resources contains
at least identifiers associated with those communications devices
to which transmission resources are allocated in the set. By
monitoring this allocation information a communications device may
determine whether the set of transmission resources contains a
resource allocated for this communications device. Typically
allocation information contains also information indicating which
part of the set of transmission resources is allocated to a
communications device indicated in the allocation information.
Alternatively, this information may be implicit, for example, based
on the order of identifiers in the allocation information. For
example, if a set of transmission resources is allocated in
fixed-sized chunks, the order of the identifiers unambiguously
defines the resource allocation of a set of transmission resources.
Allocation information may further contain various other details,
as the order and size of the allocated resources, as discussed
below. A set of transmission resources may be allocated to a single
communications device, or the transmission resources of a set may
be allocated among a plurality of communications devices.
It is appreciated that alternatively to being associated with a
single communications device, an identifier in an allocation table
(or other allocation information) may be associated with a group of
communications devices. Group allocation allows a common indication
of resource allocation for more than one communications device at a
time. The group of communications devices are given a same group
allocation rule, and communications devices of the group monitor
the same allocation information and the same sets of transmission
resources. A communications device may have allocation rule(s)
associated with its specific identifier and/or group allocation
rule(s) associated with a group identifier. It is possible that,
especially in the downlink direction, the transmission resources
associated with a group allocation identifier are common to the
group; in other words, all communications devices of the group
receive the same information. Alternatively, it is possible to
separately inform the communications devices of the group (for
example, when setting up an allocation group) how resources, whose
allocation is notified by a group identifier, are allocated among
the group of communications device. The group allocation identifier
is advantageous, for example, for transmission of small amounts of
rare data, which is easy to align similarly for a group of
communications devices. Such examples could be data cast of similar
data for a user group, personalized group messages, personalized
info delivery, or personalized messages.
It is appreciated that a piece of allocation information associated
with a set of downlink transmission resources may specify
allocation of that set of downlink transmission resources only.
It is appreciated that a piece of allocation information associated
with a set of uplink transmission resources may specify allocation
of that set of uplink transmission resources only.
Alternatively, a piece of allocation information associated with a
set of downlink transmission resources may specify allocation of
that set of downlink transmission resources and allocation of a set
of uplink transmission resources. If the allocation of uplink and
downlink transmission resources is the same, the allocation
information need not specify the direction of the allocated
transmission resources. If the allocations of uplink and downlink
transmission resources are independent, the allocation information
specifies separately allocation for the set of downlink
transmission resources and for the set of uplink transmission
resources. This can be done, for example, by having two separate
allocation tables, one for downlink another for uplink, or by
having link direction indicators in a single allocation table.
In embodiments of the invention, at least one allocation rule is
defined for a communications device that wishes to transmit or
receive information in a discontinuous manner. An allocation rule
defines typically a sequence of sets of transmission resources,
which may contain transmission resources allocated for a given
communications device. The communications device thus need to
monitor allocation information of the sets of transmission
resources defined by its allocation rule(s) only, and the
communications device need not decode allocation information of
resources of all sets of transmission resources, intended for other
communications devices respectively. If the allocation information
of a given set of transmission resource indicates that this set
contains a transmission resource allocated for this communications
device, the communications device typically receives and/or
transmits information using this allocated transmission
resource.
By defining at least one allocation rule for a communications
device and by allocating transmission resources in accordance with
the allocation rules, a communications device knows when is the
next instant in time that it may receive/transmit information in a
discontinuous manner. The communications device need not monitor
allocation information continuously to find out when transmission
resources are next allocated to it. This reduces power consumption.
Depending on the information transfer need, different allocation
rules may be defined. Some examples of allocation rules are
discussed in more detail below.
The communications system, on the other hand, may decide about the
actual allocation of resources based on the allocation rules and
various other factors. This means that for each communications
device there are certain sets of transmission resources, which
potentially contain transmission resources allocated to that
communications device. Depending, for example, on the need to
allocate transmission resources to the communications device and on
the transmission load, the communications system then allocates
transmission resources for a communications device among the sets
of transmission resources potentially containing transmission
resources for this communications device.
It is appreciated that even if every resource allocation in
subsequent sets of transmission resources is independent, the
allocation information does not appear in an independent way, but
the allocation information is favorably linked to consequent
allocation indications by defined allocation rules. From the system
point of view, it may be advantageous to arrange communications
devices so that each follows its favorable allocation rules for
potential decoding of allocation indications, instead of decoding
all allocation indications. This is discussed in more detail below
in connection with FIGS. 5a to 5e.
FIG. 2a shows a flowchart of a method 200 in accordance with a
first embodiment of the invention. The method 200 relates to
allocation of transmission resource to communications device and
how to indicate the allocated transmission resources to the
communications device. As discussed above, allocation of a set of
transmission resources is indicated to communications devices with
allocation information associated with said set of transmission
resources (step 201). This allocation information may be, for
example, an allocation table transmitted in the beginning of a
frame. Typically allocation information of a set of transmission
resources in the downlink direction is transmitted together with
information carried by the set of transmission resources.
Allocation information of uplink set of transmission resources may
be transmitted, for example, in connection with a corresponding set
of transmission resources in the downlink direction or separately
at time instants defined for the uplink sets of transmission
resources. In step 202, at least one allocation rule is defined for
a communications device. The allocation rule associates typically a
sequence of sets of transmission resources with the communications
device. This sequence of sets of transmission resources may contain
transmission resources allocated for the communications device. As
discussed above, a communications device monitors allocation
information of those sets of transmission resources defined by its
allocation rule(s). In step 203, the communications devices are
informed about their respective allocation rules. The
communications devices need not know allocation rules of other
communications devices. The communications device may receive
information explicitly defining an allocation rule. As a further
example, there may be a set of default allocation rules, and the
communications device receives an identifier associated with a
default allocation rule. Transmission resources are allocated for
communications devices based at least one of their allocation rules
in step 204.
FIG. 2b shows a flowchart of a method 210 of operating a
communications device in accordance with the first embodiment of
the invention. In step 211 at least one allocation rule defining a
sequence of sets of transmission resources associated with the
communications device is determined. Typically, the communications
system sends to the communications device information about its
allocation rule(s). A communications device may propose a suitable
set of allocation rules for itself, and the communications system
may then confirm which set of allocation rules will be in use. As a
second example, the communications system may propose some sets of
rules to the communications device, which then selects the most
appropriate rule(s). The second embodiment below discusses this in
more detail. In step 212, the communications device monitors
allocation information of said at least one set of transmission
resources defined by its allocation rule(s). In step 213 the
communications device determines, based on the monitored allocation
information, whether said sequence of sets of transmission
resources contains transmission resources allocated for the
communications device.
FIGS. 3a, 3b and 3c show schematically some examples of allocation
rules using radio frames as an example. In FIG. 3a, a
communications device 101 has an allocation rule defining that the
communications device 101 monitors allocation information in frames
periodically. The period may be defined as a number of frames or as
a time period, which ever is more suitable. In FIG. 3a, the
communications device 101 monitors allocation information of every
other frame 301, 303, 305 by the way of example. The communications
device 101 may completely ignore allocation information in frames
302, 304 and 306, because it knows that these frames cannot contain
transmission resources allocated for it. In FIG. 3a, allocation
information of frames 301 and 305 indicates an identifier
associated with the communication device 101. Allocation
information in these frames also tells to the communications device
101 which transmission resources in the frames are allocated for
the communications device 101 (hatched part of frames 301 and 305).
Accordingly, the communication device 101 can receive information
correctly. In FIG. 3a, allocation information in frame 303 does not
include an identifier associated with the communications device
101, which means there were no actual resources allocated for
communications device 101 in this frame.
It is appreciated that the allocation information may alternatively
or additionally relate to uplink frames. In this case, the
communication device 101 would transmit information using the
transmission resources allocated to it.
A periodic allocation rule may define a sequence of sets of
transmission resources using a time period or, for example, a
number of sets of transmission resources. When a set of
transmission resources is a frame, a periodic allocation rule may
use a System Frame Number (SFN). The communications device can
typically keep track of the system frame number without receiving
all frames, and therefore SFN is very suitable in uniquely
identifying frames. The periodic allocation rule may define every
n'th frame, for example, by defining an integer value n and an
offset value 0. . . n-1. Every n'th frame for a first
communications device can be defined, for example, by the
mathematical modulus operation, as the following notation: offset
{0} SFN mod n, where mod stands for the modulus operator. For a
second communications device, every n'th frame period with a
different offset can be defined, for example, as offset {1} SFN mod
n.
For different communications devices, the modulus and offset values
may be set differently depending, for example, on their
communication needs, their active traffic types, and/or quality
requirements. This is discussed in more detail in connection with
FIGS. 5a to 5e. The modulus values can be adjusted when the
transmission load in the communications system changes. (A skilled
person recognizes also the need to adjust the offset values
accordingly.) In a heavily loaded cell, the allocation
opportunities may appear more rarely and in a lightly loaded cell,
the allocation opportunities may appear more frequently; this at
least for traffic flows that allow such adjustments. If there is an
overload situation, the allocation rules may be adjusted by
increasing the values of modulus. As an example, the modulus value
n of all allocation rules can be multiplied by two. The result is
that the possible amount of allocated transmission resources per
time unit for each communications device is reduced to half and the
load is thus decreased. Adjusting the modulus values is possible
within the delay requirements of the traffic flow, and it is
especially suitable for data flows which are not time critical and
can wait a longer time in a buffer. It should be noted that
adjusting the modulus values is not absolutely required to mitigate
an overload situation in the down link direction. If the load is
heavy, the communication system would just not allocate the user in
all the sets of transmission resources that the user is following
according to his allocation rule. If it is desired to translate the
scarcer allocation of resources into a power saving for the
communications device, the allocation rule may be changed.
Various n values used in a communication system may be, for
example, powers of 2 (that is n=1, 2, 4, 8, . . . ). But this is by
no means the only possible choice for values of n.
If allocation information is transmitted once per superframe, an
allocation rule typically defines which frames of a superframe a
communications device monitors for allocation information. If a set
of transmission resources contains substructures, whose
reservations are individually announced, the substructures may be
identified, for example, by an identifier of the set of
transmission resources and a separator. For example, a substructure
of slots in a frame may be identified by a system frame number and
a separator. The separator may be an additional subfield or it may
be a bit-range extension to the original system frame number. It is
thus possible to use embodiments of the present invention, even if
the allocation space is more than one frame at a time or shorter
than a frame at a time.
For conversational traffic types, transmission resources in uplink
and in downlink are typically allocated to a communications device
based on the same set of allocation rules, even if the actual
allocation may occur independently to the opposite link direction.
For example, for data transmission in downlink, transmission
resources are allocated in the sets of transmission resources
defined by a periodic allocation rule, when there is data to
transmit to the communications device. Similarly, in uplink, the
communications device may be allocated sets of transmission
opportunities defined by the periodic allocation rule. This way the
communications device can indicate to the communications system
that it has more data to transmit. After receiving the first
indication, the communications system may then allocate more
precise resources to the communications device in the subsequent
sets of transmission resources, thus allowing the communications
device to send its data.
FIG. 3a shows, furthermore, uplink frames 301a, 302a, 303a, 304a,
305a and 306a as an example of uplink sets of transmission
resources. The uplink frames in FIG. 3a illustrate functionality of
frequency division duplex (FDD), where transmission and reception
in the uplink and downlink directions occur at different
frequencies. The allocation information in the downlink frames 301,
303 and 305 informs the communications device 101 whether
transmission resources have been allocated this communications
device in the uplink frame 301a, 303a, and 305a. The timing offset
between DL and UL frames in FIG. 3a is only exemplary. The UL and
DL frames may be aligned or offset, or they may even be of
different length and size. An alternative for the Frequency
Division Duplex (FDD) arrangement may be a Time Division Duplex
(TDD) arrangement, where the downlink and uplink operate on the
same carrier frequency.
FIG. 3b shows schematically an example where there is a first
allocation rule with a longer period (rule#1 in FIG. 3b) and a
second conditional allocation rule with a shorter period (rule#2 in
FIG. 3b). The first allocation rule may be called a long-term
allocation rule and the second allocation rule may be called a
short-term allocation rule. Consider an example, where a
communications device 101 is transmitting and receiving voice data.
Voice codecs typically output a voice packet periodically, and
therefore the communications device wishes to transmit a voice
packet periodically. For supporting voice data transmission from a
communications device, it is sufficient to define a periodic
allocation rule (rule#1). The communications system then allocates
transmission resources in all downlink and/or uplink frames as
defined by the allocation indication present according to the
periodic allocation rule.
For voice frames received from the codec at the other end of the
voice connection over a network and transmitted to a communications
device, there may be transmission delay jitter caused by the
network itself. This is especially true for a packet-switched
network, where routing queues and routing algorithms will cause
variable packet delays. Consider the example in FIG. 3b, where the
long-term rule (rule#) defines that frame 311 is expected to
contain a voice packet for the communications device 101. If a
voice packet is not available for transmission to the
communications device 101 in frame 311, it is typically not
possible to delay the transmission of the voice packet until the
next frame 319 defined by the long-term (every-eight-frame)
allocation rule. Therefore, if the communications device 101
notices that a frame 311 defined by the long-term allocation rule
does not contain transmission resources allocated for this
communications device 101, it starts to use the short-term
allocation rule (rule#2). The short-term allocation rule may also
be a periodic rule. In FIG. 3b, the short-term allocation rule
(rule#2) defines that the communications device 101 monitors
allocation information of every subsequent frame. The communication
device 101 notices that frame 312 does not contain transmission
resource allocated for this communications device. Frame 313, on
the other hand, has transmission resource allocated for this
communications device. After finding transmission resources
allocated for itself in a downlink frame defined by the short-term
allocation rule (and correctly receiving the information carried by
the allocated transmission resources), the communication device 101
returns to using the long-term allocation rule. This way the
long-term allocation rule and the short-term allocation rule may
alternate in order. As frames 319 and 327 contain transmission
resources allocated for the communications device 101, it does not
employ the short-term allocation rule after these frames.
It is appreciated that the allocation of uplink and downlink frames
for voice data (or other data flow with expected transmission time
interval) need resources based on a long-term allocation rule. For
an associated data flow, a conditional short-term allocation rule
is typically needed in addition to the long-term allocation rule.
It is also possible to specify an independent long-term allocation
rule and an independent short-term allocation rule for a
communications device 101. Associated data flow here means that the
forward-flow is tightly coupled to the reverse-flow, or vice versa.
An example of this is TCP acknowledgements, which always follow a
delivery of a segment to the other link direction. Other examples
are interactive or transaction traffic-flows, where a given
initiation-action determines the response-action to the other link
direction. Thus, traffic characteristics and transmission needs of
forward and reverse links are coupled.
As a second example of usage of a conditional short-term allocation
rule, consider retransmission of data when the reception of the
data fails for some reason. If the communications system does not
receive data from the communications device 101 or an
acknowledgment of receipt is lost or when the communications device
101 sends a negative acknowledgement of receipt, the communications
system typically retransmits information in accordance with a
short-term transmission rule until a positive acknowledgment is
received from the communications device 101. The communications
device 101 may be triggered to use this short-term rule for
allocation information monitoring in response to an unsuccessfully
received piece of information, and the communications system
allocates resources for the retransmission based on the short-term
allocation rule. Similarly, if the communications device 101 does
not receive a positive acknowledgement in response to data
transmitted to the communications system, this may be indicated to
the communication system, and the communications system may start
to allocate transmission resource for uplink retransmissions based
on a short-term allocation rule. The communications device 101
monitors allocation information in accordance with the short-term
allocation rule and retransmits information when having noticed
transmission resources allocated for itself in the uplink
direction.
FIG. 3c refers to a third example, where two periodic allocation
rules are used in combination. Here the first periodic allocation
rule is used to allow the communications device 101 to check
allocation information only quite seldom (for example, in frames
330, 360, 390). If the communications system has data to transmit
to the communications device 101, the communications system may
indicate this by announcing start of transmission in one of the
sets of transmission resources defined by the first periodic
allocation rule. In FIG. 3c, the start of transmission is announced
in frame 360. This announcement may be in the allocation table or
in the payload carried by that frame. Thereafter the communications
device 101 switches to apply a short-term rule for monitoring
allocation information. In the example in FIG. 3c, the short-term
rule defines that the communications device 101 monitors allocation
of each subsequent frame 361, 362, . . . , 371. In frame 371, the
allocation information no more indicates allocated transmission
resources for the communications device 101, and thus the
communications device knows that it should again switch to apply
the long-term allocation rule for monitoring. The next frame, whose
allocation information the communications device 101 monitors, is
frame 390 in accordance with the long-term allocation rule.
For a communications device to be able to transmit information in
the uplink, the communications system may allocate transmission
resources based on a long-term rule. Once having transmission
resource allocated in the uplink, the communications device may
indicate to the communications system that it has data to transmit.
This indication may be, for example, transmission of a piece of
data waiting transmission using the resources allocated based on
the long-term rule. Alternatively, the communications device may
indicate the amount of data (together with the actual delivery of
the first part of data) it has available for transmission.
Thereafter the communications device may start to monitor
allocation information in accordance with a short-term rule and to
transmit information when it notices that there are transmission
resources allocated for it in the uplink direction. Once there is
no more data to transmit in the communications device (or the
communications device has transmitted as much data as it desires to
transmit currently), the communications device may simply stop use
of transmission resource allocated to it or the communications
device may indicate it has no more data. In response to noticing
unused allocated resources, the communications system may start
allocating transmission resources in the uplink based on the
long-term rule and the communications device may start monitoring
allocation information in accordance with the long-term rule.
Devices transmitting non-delay-sensitive data every now and then
could use this kind of transmission scheme.
A further example of an allocation rule is a rule that refers to a
sequence of sets of transmission resources starting from a given
future set. This sequence of sets starting from a given future set
of transmission resources may be called a continuum. The future set
of transmission resources, where the next continuum begins, may be
identified, for example, by a sequence number of the set or by a
time instant at which the future set of transmission resources is
transmitted/received. The communications device starts to monitor
allocation information at the given future set and continues this
monitoring (possibly in accordance with a short-term rule) until
told otherwise. The communication device is told to stop using the
short-term allocation rule by giving, for example, in a payload of
one of the sets of transmission resources of the current continuum
a pointer to a next future set of transmission resources of the
next continuum. The set of transmission resources containing the
pointer to the next continuum is typically defined to be the last
set of transmission resources in the current continuum.
The short-term allocation rule which the communications device uses
for monitoring allocation information starting from the given set
of transmission resources may be implicitly known, or a short-term
allocation rule for a next continuum may be explicitly specified
together with the pointer to the next continuum.
It is possible that--in addition to the payload containing the
pointer to the next continuum--there are no other transmission
resources allocated for the communications device in the present
continuum. As an alternative to the allocated payload, the pointer
to the next continuum may be in a piece of allocation
information.
It is possible that there is defined a set of allocation rules for
each connection. Here a set of allocation rules refers to one
allocation rule or to a combination of allocation rules. As an
example of a combination of allocation rules, consider the above
discussed combination of two periodic allocation rules with
different periods) for each connection. In this case, the
communications device 101 should contain functionality to monitor
allocation information as defined jointly by the flow-specific or
connection-specific (typically uniquely defined by the Internet
Protocol address and the port number) allocation rules.
Alternatively, it is possible to define a set of allocation rules
for a communications device. This communications-device-specific
set of allocation rules should meet transmission requirements of
all flows (connections) of a communications device. The
communications system may contain functionality for determining
device-specific allocation rules based on requirements of the
connections. The communications system may contain functionality
for determining device-specific allocation rules based on the
capability of the communications device. Examples of how the
communications system and the communications devices can keep
information about allocation rules are discussed in some detail
below in connection with a second embodiment of the invention.
In the following, a second embodiment of the invention is
discussed. In this second embodiment, a set of transmission
resources is a radio frame and an allocation table in the beginning
of a downlink radio frame is a specific example of allocation
information. Other examples of allocation table placement in a
frame are center of the frame, a special placement in the frame as
close to the pilot symbols or training sequences. The allocation
table may refer to transmission resources in the same downlink
frame that it is placed in, and/or to any following frame.
Similarly, the allocation table may refer to transmission resources
in any upcoming uplink frame. Furthermore, identifiers of
communications devices in the allocation table are radio link
identifiers (RLID) or group allocation identifiers. It is evident
that any features discussed in connection with the second
embodiment, which are not applicable only to radio frames, to an
allocation table in the beginning of a downlink radio frame or to
radio link identifiers, are applicable also on a more general
level. Furthermore, in connection with the second embodiment, a
communications device is called a terminal and a transceiver
network element is called a base station.
An idea in the second embodiment is to form parametrisable
AllocationTables, which are separate from each other. Radio Link
Identifier (RL ID) identifies the allocation for each terminal, as
RL ID is unique for any terminal in any cell. It is also assumed
that the allocation identification cannot be a priori ordered,
because the traffic requirements (buffer status and delay) will
change from one AllocationTable to another. For each instant of the
AllocationTable, it is necessary to include RL IDs of all those
terminals, which will get allocation, and it is necessary to signal
their order of allocation, if not otherwise obvious. The order in
which RL IDs are listed in the AllocationTable entry is one way to
announce the order of allocation. If the order and size of
allocation are not coupled, additional bit fields are needed to
announce the order and size of allocation in resource units.
In this second embodiment, the AllocationTable may be assigned an
identifier so that the terminals know which AllocationTables to
monitor. A reasonable separator for AllocationTables is System
Frame Number (SFN), which is a long unique sequence, which
identifies frames uniquely and is commonly available for the
communications system and for all communications devices operating
therein. AllocationTable identifiers may be implicitly calculated
and they need not be signaled frequently. Some initial signalling
may be necessary to negotiate between the base station and the
terminal, which AllocationTables this terminal follows, that forms
the allocation rule. This depends, for example, on the active
traffic flow types of the terminal and load situation of the
network. As discussed above, uplink and downlink AllocationTables
may be separate and they may follow a separate allocation rule.
However, these tables may be joined, and just the link direction
need to be indicated for every allocation. If the rule for
AllocationTable for a given terminal changes, that has to be
signaled to the terminal. This may happen, for example, when a
traffic flow is activated, modified or terminated.
FIGS. 4a and 4b show schematically procedures for negotiating and
assigning allocation rules for the downlink and uplink directions,
respectively. In downlink, the base station may assign an
allocation rule for a terminal based on its knowledge about, for
example, the following: terminal capability Full-Duplex/Half-Duplex
traffic flows active in downlink and uplink downlink criteria
separately from uplink criteria downlink criteria to satisfy uplink
traffic criteria traffic flow characteristics traffic flow delay or
bit rate requirements traffic buffer status
The base station informs the terminal about the allocation rule by
sending an allocation rule assign message 401. The terminal will
verify the allocation rule and check, if it can meet these
requirements in terms of capability and whether this allocation
rule would satisfy its expectations for the downlink traffic. If
the terminal accepts and is able to satisfy the rules, it will send
a confirmation message 402 to the base station. Otherwise, the
terminal will not confirm the rules but will propose modifications
to the rules instead. If the terminal needs more tight allocation
rules, it may propose them to the base station separately. On the
other hand, if terminal wants to have more loose allocation rules,
for example, to have longer DTX or DRX periods, it may propose this
as well to the base station. Alternatively, it is possible that the
base station will assign a set of possible allocation rules in the
allocation rule assign message, from which the terminal has to
select one and response this choice in the allocation rule confirm
message.
In uplink, the terminal will make a request for getting uplink
allocation by sending an allocation rule request message 403. This
request may already include a proposal for the allocation rule. The
base station will verify and check, if it can meet the requirements
(for example, in terms of channels available and load) this
proposal sets and whether this rule would satisfy its expectations
for the uplink traffic. If base station is able to satisfy the
rules, it will send a confirmation message 402 to the terminal. If
the base station wants or needs to modify these rules, it will
respond to the terminal with an allocation rule assign message 401
in addition to the negative confirmation message 402. Uplink
allocation rule may be based on the knowledge about, for example,
the following: terminal capability Full-Duplex/Half-Duplex traffic
flows active in downlink and uplink uplink criteria separately from
downlink criteria uplink criteria to satisfy downlink traffic
criteria traffic flow characteristics traffic flow delay or bit
rate requirements traffic buffer status measured pilot signal
strength
The messages necessary for negotiating the allocation rules may
belong either to a stand-alone procedure or the information
contents of these messages may be embedded as Information Elements
to some other suitable procedure or to the messages of this other
procedure. These messages may be placed in the access channels, for
example, random access, direct access or forward access channels or
as well to dedicated or shared channels.
FIG. 4c shows, as examples, protocol messages for carrying
allocation rule negotiation and assignment. FIG. 4c shows a
possible protocol message structure for carrying the allocation
rule request message 403, the allocation rule assign message 401,
and the allocation rule confirm message 402. The protocol header
includes, among other definitions, a Control/Traffic (C/T) flag
411, which describes, whether the payload includes a signalling
message (C/T=C) or user plane traffic (C/T=T). For control message
and for user plane traffic payload, the segmentation sizes may be
different. When ever control protocol data units (Pdus) are set
into a given resource unit, it is optional whether there can follow
user traffic payload Pdus in the same resource unit during the same
Transmission Time Interval (TTI) or if they have to be multiplexed
into a separate TTI.
FIGS. 5a to 5e illustrate different possible ways for using
allocation rules. The System Frame Number SFN is available in this
second embodiment, and it can serve as the time descriptor of the
AllocationTable. SFN allows a different AllocationTable appear for
each frame, and it allows this in a unique way over a very long
period of time. Say, if the optimum maximum number of active users
identified in AllocationTable is 8 and there are up to 8 active
users any allocation of these 8 users may appear at any time, see
FIG. 5a. If there are between 8 and 16 active users, their
allocations could be conveniently split to two AllocationTables,
see FIG. 5b. Respectively for 32 users, the allocation may be split
to four tables, see FIG. 5c. If all 16 users in FIG. 5d have
frequent data, then a given set of 8 users could be present in
every second frame, offset{0} SFN %2 (modulo) and the other set of
8 users in every second frame as offset{1} SFN %2. This allows that
each terminal would know, in which AllocationTable its allocation
may be announced and thus it would only need to follow every second
AllocationTable. Further on, the terminal knows its RL ID in that
AllocationTable. There is not much penalty of dividing terminals
between several AllocationTables. On the other hand it adds a small
delay, but it saves in signalling and allows Discontinuous
Reception (DRX) and/or Discontinuous Transmission (DTX). In many
typical situations, the allocations need not be that frequent.
As a function of number of active terminals in the sector, the
terminals may be split to any chosen number of AllocationTables,
which are announced as SFN %n AllocationTable. Each set of 2, 4 or
8 terminals follow a separate AllocationTable, first set with
offset{0}, second set with offset{1}, third set with offset{2} and
so forth to the offset{(n-1)}. This is illustrated in FIG. 5d,
which shows allocation for 20 active users. Each user follows
AllocationTables by SFN %4 rules; terminal #1-#2 follow offset{0},
terminals #3-#10 follow offset{1}, terminal #11-#14 follow
offset{2} and terminals #15-#20 follow offset{3}.
If the traffic volumes are not equal, the resource allocations need
not be equal for different terminals, further the AllocationTable
rule need not be equal for different terminals. A terminal with
high traffic volume may be assigned SFN %1 AllocationTable, or SFN
%2 AllocationTable rule. This means that the terminal may receive
data in every frame or every second frame respectively. The other
terminals may still follow any other SFN %n allocation rule. The
only requirement is that both the base station and the terminal
know, which allocation rule the AllocationTable may follow. This is
illustrated in FIG. 5e, where terminal #1 follows SFN %1
AllocationTables, terminal #2 follows SFN % 2 AllocationTables,
terminal #3 follows SFN % 4 AllocationTables and all others follow
some other AllocationTable rules. It is possible that some
terminals do not have allocation rules, but they follow all
allocation tables. This, however, consumes terminal power.
It is appreciated that another differentiator for AllocationTable
rule of different terminals is the delay characteristic of their
active traffic flows. A terminal with delay sensitive traffic may
be assigned SFN %1 AllocationTable or SFN %2 AllocationTable rule.
The other terminals with less delay sensitive traffic flows may
then follow a less frequent SFN %n AllocationTable rule.
FIG. 5f shows schematically an example relating to the use of a
group allocation identifier. Several terminals may be allocated a
single common group allocation identifier (Alloc_ID), which can be
used for their joint allocation reference. Use of Alloc_ID saves
signalling space in the AllocationTable, as for joint allocation,
signalling of a single Alloc_ID is sufficient instead of several
RL_IDs. The group allocation identifier sets the requirement that
allocations and DTX/DRX patterns of the connections under the
Alloc_ID follow exactly the same pace, pattern and resource
sharing. Of course, any of the connections may still have their
independent allocations and DTX/DRX rules signaled by their
individual RL_ID. As discussed above, there may be defined separate
information specifying the allocation of resources associated with
the group allocation identifier. These group rules are valid for
those allocation periods, whenever the allocations are announced by
that Alloc_ID. In a group allocation, the allocation contents may
still be unique for each user, but in this case there has to be
a-priori arrangement (in other words, the group rules) of those
allocations inside the common resource unit pointed by the
Alloc_ID. For example, four users may receive pieces of
personalized data. In this case their allocation is common, but the
resource is shared among those four users for every event of
allocation, as shown in FIG. 5f.
FIG. 5f relates to a situation where terminals UE#7, UE#15, UE#39
and UE#45 are determined to follow a common allocation rule.
Therefore, each of these terminals, is signaled that in addition to
their RL_ID indication for individual allocations, they have to
follow a group allocation announced by Alloc_ID, given here as
#158. When the allocation is announced by the Alloc_ID #158, the
terminals will always get a common allocation with a common DRX
cycle. In this allocation, the terminal UE#7 will get the first
share of size 1/5 of the allocated resource unit, terminal UE#15
will get the second share of size of the allocated resource unit,
terminal UE#39 will get the third share of size 1/5 of the
allocated resource unit and terminal UE#45 will get the fourth
share of size 1/5 of the allocated resource unit respectively.
Use of allocation rules for defining which allocation tables a
terminal monitors provides a benefit both for the base station and
the terminals as the signalling overhead in AllocationTable will
reduce. It is obvious that the more allocations are signaled in a
single table the more bits this signalling consumes. If every
allocation table includes less allocations to signal, less
signalling bits are needed. This does not impact the actual amount
of resources each connection may get over time. It will also
provide significant benefit for the terminal, as it may apply
discontinuous transmission and/or reception mode (DTX/DRX) as it
knows the rule, how frequently and at which frame it has to decode
the AllocationTable. As discussed earlier, the actual allocation
identified by that specific AllocationTable may still become
largely different. For each AllocationTable, it is possible that
the terminal did not get any allocation at all. If it got an
allocation, its allocation order in the frame may be variable, the
number of allocated resource units may be variable and the
Transport Format (Link Adaptation) may be variable defined by an
allowed Transport Format set. The Transport Format includes, for
example, modulation, channel coding, spreading, multiantenna
diversity or MIMO transmission type. The Transport Format may be
indicated in the Allocation Table. For a group allocation, the
transmission format of all users in a group may be the same, or
they may be separately indicated. The benefit of the
AllocationTable rule is obvious as it at least reveals, when the
terminal need not receive any AllocationTable and when the terminal
at least does not have any allocation. This enables DTX/DRX, which
allows significant power savings at the terminal, as some
power-hungry circuitry may be switched off during DTX/DRX.
A note about the radio channel conditions. The next DTX/DRX
activity may happen much further in the future than the channel
coherence time. This does not dictate, how long the allocation
after the DTX/DRX silence will last, nor it dictates the link
adaptation format during the next activity. During the next
activity, after the DTX/DRX period silence, any link adaptation,
MIMO and such scheme is available even if the radio channel changed
from the previous period, if channel feedback knowledge is
available. Also scheduling, packet scheduling or such, allows to
place the payload to constructive channel conditions during
activity, if channel feedback knowledge is available.
The allocation rules may depend, for example, on the following:
number of active traffic flows, type of active traffic flows, delay
requirements of active traffic flows, bit rate requirements of
active traffic flows, terminal capability as Full-Duplex or
Half-Duplex, data volumes in the buffers and load of the
network.
As also discussed above, the allocation may be independent for
uplink and downlink, may be coordinated for uplink and downlink or
may be tightly coupled, say uplink reverse flow is determined by
the respective forward downlink traffic flow or downlink reverse
flow is determined by the respective forward uplink traffic flow.
The AllocationTable may contain separate AllocationTable instances
for uplink and downlink or they may be announced in a single
AllocationTable with the link direction indicator.
In this specific second embodiment, the AllocationTable thus
include: RL_ID Allocation order (optional) number of allocated
resource units (or other kind of allocation indicator) link
direction Transport Format Channel coding Modulation Retransmission
format (IR, HARQ) SISO/Diversity/MIMO transmission
An entry of the AllocationTable may be given as
AllocationTable_SFN.RL_ID.allocation_order.#Resource_units.link_direction-
.Transport_Format
As an example of the group allocation, an entry of the
AllocationTable may be given as AllocationTable_SFN.Alloc_ID.order
in Alloc_ID list.share of the common
ResourceUnit.link_direction.Transport_Format
For processing allocation information in an AllocationTable, the
terminal typically performs time and frequency synchronization,
filtering, frame structure capturing, channel estimation,
demodulation, channel decoding, error detection for the
AllocationTable, and reading and interpreting the bit-fields in the
AllocationTable. Thereafter the terminal can decide whether its RL
ID or/and Alloc ID was present in the AllocationTable. In case
either one identifier or both identifiers were present, the
terminal acts accordingly to transmit and/or receive the actual
payload in the set of transmission resources.
In the following, the long-term allocations for traffic types with
known expected transmission time intervals (TTI) are discussed.
Above reference was made to long-term allocation rules, and the
expected TTIs can be used for determining the monitoring period for
these long-term allocation rules. As examples, voice, audio and
video are discussed below in detail. It is possible to determine
the expected TTI, for example, by finding out which type of data is
transmitted and/or which codec is used for coding the data. It is
appreciated that the details of how the expected TTI is determined
is outside the scope of this present invention. The present
invention concentrates on using a known TTI for determining
allocation rules. Any TTI value may be allowed, for example
well-known values of 1 ms, 2 ms, 10 ms, 20 ms, 40 ms, 80 ms up to
100 or 200 ms are typical.
Among the terminals, there may be traffic source activations, which
are known to follow certain natural inter-arrival process. An
example is voice service, where the voice codec, if AMR (Adaptive
multi-rate) or AMR-WB (Adaptive multi-rate Wideband), is known to
provide a voice frame every 20 ms, which is the duration of a
phoneme. Quantisation and coding of voice is thus processed in 20
ms periods, which forms a voice frame with scaling factors and
subband samples inside the frame. Once a voice frame is created, it
will be embedded into a Real-Time Transmission Protocol (RTP)
packet. The next voice frame and next RTP packet will appear after
20 ms. Similar natural inter-arrival process exists for audio
signal. Natural inter-arrival process exist as well for video,
where quite typically some 25 picture frames are created per second
and a picture update packages appear at 40 ms intervals.
Depending on the settings, the voice codec will provide one packet,
whose length is variable depending on the amount of information
that the codec generated. Typically the voice frame size is
constant for a given audio quality setting, in other words, for a
given audio quality setting there is provided a constant bit rate.
For adaptive bit rates, the payload is of variable size, but the
creation interval is constant.
Regarding voice, one voice frame and one RTP/UDP packet is
preferably delivered in a single IP packet, and it follows about 20
ms inter-arrival time. However, it is optionally possible to
aggregate more than one voice frame, say two or four even up to
eight voice frames to a single IP packet. However, aggregation like
this makes the payload more vulnerable to packet loss and more
sensitive to delays compared to a single voice frame per IP packet
transmission.
The size of allocation (over the air interface) that each voice
packet requires per 20 ms arrival instant depends, in addition to
the voice frame length, on the length of the IP, UDP, RTP and such
headers, on the IP header compression scheme and its header
compression state. If no compression is applied, the overhead is
several tens of bytes per voice frame and is thus excessive. Header
compression will reduce the overhead to minimum possible at each
instant. The compression result also depends on the checksum fields
applied on different protocol layers, because checksums do not
compress away. Further, at some transmission instants, some reverse
flow header compression ACK may add to the compressed forward flow
headers. The compression is able to handle IPv4 and IPv6 and
further UDP and RTP protocols. Header compression means are
specified in RFC3095 (ROHC) and RFC2507.
In Internet, there are versatile implementations of voice codecs,
which may provide uncompatible formats and frame structures. The
voice quality of such codecs over a communication link is typically
lower than voice quality of AMR and AMR-WB codecs. The
AllocationTable allows delivery of any voice format by allowing
variable payload length be allocated.
Regarding audio coding, there exist several codecs and codec
settings. There are MPEG players (for example, MPEG2 layer II,
MPEG2 layer III, and MPEG4), Media players, MP3 players and such.
They sample and create frames for the full audible band up to 64
kHz, whereas voice codecs often code only the voice band up to 4
kHz or up to 8 kHz. The audio frame length is defined by the audio
codec specification. Typically, each audio frame contains a
constant number of samples. This will result audio frame creation
interval, which is typically of orded somewhat above 20 ms (depends
on the audio codec). One audio frame is typically inserted into one
RTP packet. If the amount of audio frame information is above the
Maximum Transmission Unit (MTU) packet size, multiple RTP packets
will be created. RTP time stamp uniquely describes timing of audio
frames. In some exceptional cases, samples from more than one time
stamp period may be collected to the same RTP packet, for example,
if the payload of each frame is very small. For this situation,
there are special time stamp creation rules. For an audio decoder,
there exist bit buffers at the input of the decoder and also
play-out buffers, which do some traffic smoothing.
For video transmission, several codecs and coding settings are
valid. Quite typically a single picture is created in 40 ms
intervals, as 25 pictures per second is enough to hide
discontinuity of moving video from the user. For creation of a
picture frame of video transmission, there are diverse types of
coding algorithms. Sometimes a picture with full information is
delivered, sometimes a differential picture is formed and
delivered. The amount of information thus varies a lot from one
picture coding interval to another interval. The picture is
delivered in number of variable length packets per picture coding
interval. For a video decoder, there exist bit buffers at the input
of the decoder and also play-out buffers, which do some traffic
smoothing.
As the created video frames are typically carried in IP packets,
there are various routing paths and load conditions over the
networks, which will cause delay and delay jitter to the packet
arrival process at the base station buffers for downlink traffic.
In the terminal, the packet creation process to the transmitter
buffer has much less delay jitter as packets do not traverse
through the network before getting uplink allocation. In the
downlink, the base station knows the buffer status and may make
optimal and precise allocations of resource units at each frame
time into the AllocationTable. In the uplink, the buffer status is
not known by the base station, which announces the allocations.
Here, terminal has to signal its buffer status, request for an
amount of allocation or has to allow base station to allocate some
nominal amount of resource units, which the terminal may then use
and indicate further how much more consequent allocation is
needed.
For this allocation method, known characteristics of the traffic
flows give an opportunity for the terminal not to decode
AllocationTables at all time instants when they appear. If the
terminal has an active traffic source of voice/audio/video/data, it
may be reserved an allocation approximately every inter-arrival
time periods of times. Say, AllocationTable announced that the
terminal has a voice packet to receive, the terminal will receive
the packet for decoding. So, if the previous allocation was at SFN,
the next AllocationTable to decode will appear determinedly at
SFN+Transmission Time Interval (TTI) and the terminal knows that
for this voice service traffic flow, it need not decode any of the
AllocationTables until The TTI has elapsed, that is at
AllocationTable_SFN+TTI.RL ID.
As discussed also above, because of the delay jitter it may happen
that the packet arrived to the base station buffer already before
the inter-arrival time or did not yet arrive. In the first case,
the base station will just delay the packet a little and will
create the AllocationTable_SFN+TTI.RL ID allocation indicator at
the proper time instant and allocate resource for the packet
respectively. The cost of delaying this early packet is not large
and it does not harm much. In the second case, there is no packet
to deliver and the base station need not have that RL ID present in
the AllocationTable. However, the terminal needs to do more
frequent reception of the AllocationTable, as the packet may arrive
at any instant after the inter-arrival time elapsed. If in this
case, the terminal would wait for another TTI, the packet that
arrives soon after the first TTI elapsed, would be too much delayed
and the inter-arrival process would be disturbed.
After the skip of one TTI, if there is no downlink data to be
allocated, the base station could inform the terminal, how it has
to follow decoding the AllocationTables. There are several ways of
implementing this. The terminal could know a priori interval for
following, say every 4th or 8th AllocationTable after the TTI
elapsed. Then it is determined that resource allocation will happen
as soon as possible in any of the AllocationTables in that
sequence. After the allocation was active, new inter-arrival
waiting time will be activated for the next packet arrival. Here,
the inter-arrival time is activated based on the expected
inter-arrival time so if there is jitter, each new TTI waiting time
is activated based on the inter-arrival time plus the expected
previous inter-arrival to compensate delay jitter in the expected
value as much as possible. (Any expectation value technique may be
applied.)
It is appreciated that several variants may be tailored for
transmitting data based on TTI. The natural inter-arrival time may
be reduced somewhat to start decoding AllocationTables for possible
allocations in case of early arrival. Another variant is that
AllocationTable allocation opportunity is reserved at the frequency
of for example two times or four times the expected inter-arrival
times. This allows delayed packets still be delivered in timing
requirements. It will also allow time for physical layer
retransmissions, which are important to increase the probability of
correct decoding by recovering packets that corrupted during the
first transmission by incremental redundancy, by retransmitting
replicas or by soft-combining.
FIG. 6 relates to a combination of short-term and long-term
allocation rules for three terminals. The allocation rule may
include definitions for a short-term allocation and for a long-term
allocation separately. The long-term allocation rule may be tied to
an expected TTI, which is typically a very long period compared to
the frame. In the AllocationTable after the TTI, if the allocation
is empty (that is, data was not available for transmission in the
buffer), the terminal and the base station will start following the
short-term rule. This could mean that the allocation opportunity
would appear, say every SFN %4 AllocationTable offsetting by
offset{x}. The terminal will thus continue decoding the
AllocationTables until it received a packet. If there is no
continuum announced in this packet and if the terminal decodes it
correctly, it can again switch to the long-term allocation rule.
This means, it will decode the next AllocationTable at the expected
TTI announced by the long-term allocation rule. Long-term
allocation rule is illustrated in FIG. 6. Short-term allocations
are shown in the same Figure. For the first terminal (marked with
white blocks) there is a long-term allocation interval of TTI,
accompanied with short-term allocations for excess data and
retransmissions. For the second terminal (marked with blocks having
a lighter shade of gray), there are only short-term allocations,
regularly in every second frame. For the third terminal (marked
with dark gray blocks), there are also only short-term allocations,
regularly every fourth frame.
After any allocation and reception of packets, there may be a
continuum announced. In other words, the allocation is announced to
continue until, for example, the full transmission buffer is
emptied. This continuum may be indicated to follow immediate every
frame rule or may follow the short-term allocation rule. Another
embodiment is to postpone this continuum and have dedicated
signalling to point, where (in which SFN) the continuum starts (see
FIG. 7a). The continuum may thus nicely be extended by dedicated
pointing, which always shows the start of the next piece of
continuum. FIG. 7b shows, as an example, frames allocated using a
continuum allocation rule. In the first continuum shown in FIG. 7b,
the terminal monitors allocation information of every other frame.
In frame SFN+4, there is a pointer to frame SFN+24 and, optionally,
short-term rule defining that every other frame is monitored in the
next continuum. The presence of the short-term rule for the next
continuum is not mandatory, if the terminal knows that it applies
the same short-term rule until otherwise told. In frame SFN+27,
there is again a pointer to frame SFN+44 and a new short-term rule
defining that allocation information of every fourth frame is to be
monitored.
If a packet was allocated but is not properly decoded, there will
be retransmissions of the packet. This may happen either by adding
incremental redundancy or by retransmitting replicas of the packet
or part of the packet. The base station will get to know the
retransmission need by the terminal acknowledgement. The
retransmission will be indicated by the short-term allocation rule.
So, for each TTI, a long-term allocation rule is followed and after
each TTI a short-term allocation rule is followed, until all data
is correctly received. After this period the long-term allocation
rule is again respected so that the expected TTI is calculated
without jitter, without allocation continuum and without
retransmissions. There is of course a requirement that both the
base station and the terminal calculate or know the TTI in
precisely the same way.
The criteria for assigning allocation rules are discussed next. Any
terminal may have several Layer 2 services active simultaneously
and it has to receive different types of packet traffic flows,
which have different characteristics. Thus, terminal should get
active at any time, when any of its traffic flow requirements so
determine. As there is flexibility for some traffic flows, for
example, non-delay sensitive data services, it may be possible to
coordinate their allocation for a single terminal. The base station
may arrange most favourable timing constraints for all traffic
flows of a terminal so that it will receive packets in a tight
(continuous or very frequent) allocation as a burst and will then
sleep till the next occurrence of a burst. Sometimes, the types of
traffic flows do not allow this kind of coordination and each have
to be followed at intersecting inter-arrival times.
The base station may have various optimization criteria for
assigning allocation rules. It can monitor the buffer status of
each traffic flow for every terminal and adjust the allocation
rules. If there are non-delay sensitive packet flows, they can be
used to smooth cell load. The base station will first of all take
care of satisfying very delay sensitive traffic and real-time
traffic rules. Non-real time traffic is more flexible in allocation
timing. If there is less load in the system, the base station may
divide the non-delay sensitive traffic load for any given
allocation table split, say evenly for SFN %4 allocation. If the
load or interference conditions get worse, the base station may
easily modify the allocation rule for this non-delay sensitive
traffic load to follow say SFN %8, SFN %16, SFN %32 or SFN %64 rule
and so forth. All this may happen without modifying the allocation
rules for delay sensitive or real-time traffic flows. Changing any
rules may happen by the Radio Resource Control (RRC) signalling, as
described in section 2. The modifications of short term allocation
rules could actually be applied through the AllocationTable as
well, as signalling such activation rules is not excessive bit
load.
FIGS. 8a to 8e show, as examples, various tables relating to
keeping track of allocation rules in a base station and in a
terminal. A terminal may have any combination of short-term and
long-term rules assigned to it. As discussed above, (combinations
of) allocation rules may be terminal-specific or connection
(traffic flow) specific. Information about the next continuum may
be kept in the same table respectively.
Table 1 in FIG. 8a is an example of a base station table for
allocations. In Table 1, the base station and UE1 have one traffic
flow, which follows a short-term rule (that is, one period for
monitoring allocation information). The base station and UE 2
follow one short term rule and one long-term rule without using
information about the expected TTIs. In this case, the short-term
rule may be activated after the actual allocation in a frame
defined by the long-term allocation rule is found. This way the
base station, once it decided to transmit data and indicated the
start of transmission by allocating a part of frame defined by the
long-term rule, may transmit data to terminal UE2 using allocations
defined by the short-term rule. The base station and UE3 follow a
different long-term rule for traffic flow 1 and traffic flow 2, but
they follow a single common short-term rule. As the TTI is defined
for both long-term rules, the short-term rule is activated if no
allocation is found in a frame defined by the long-term allocation
rule in order to cope with delay jitter.
Table 2 in FIG. 8b is a further example of a base station table for
allocation. Table 2 shows numeric examples relating to allocation
rules. The first terminal with RL ID 102 monitors frames with 20 ms
(which is equal to 30 SFNs, when the frame length is 2/3 ms; this
example is used widely in the numerical examples in this
description) period in accordance with the long-term rule. If
information is received and decoded correctly, this terminal
continues with the long-term rule. If information is received but
decoded incorrectly, there is need for retransmissions and this
terminal thus monitors every fourth frame in accordance with the
short term rule, typically until the information is received and
decoded correctly.
As Table 2 shows, the second terminal having RL ID 41 monitors
frames with 40 ms (60 SFNs) period in accordance with its long-term
rule. The second terminal monitors also every sixteenth frame in
accordance with its short-term rule. Conditionally, if the decoding
of received information fails in connection with the frame defined
by the long-term rule, a further short-term monitoring period is
defined (every fourth frame).
As Table 2 shows, the third terminal having RL ID 743 uses a
continuum allocation rule for monitoring allocation information.
The notation SFN+100 means that the last frame of the previous
continuum contained a pointer to skip 100 frames. The allocation
rule of the third terminal thus identifies one specific future
frame.
Tables 3 and 4 relate to Table 2. Table 3 in FIG. 8c is the
allocation table of the first terminal with RL ID 102. Table 4 in
FIG. 8d is the allocation table of the second terminal with RL ID
41. Table 5 in FIG. 8e, in turn, is an example of an allocation
table of a terminal having connections to more than one base
station. Table 5 lists a connection to a first base station, where
the terminal is associated with RL ID 41, and a connection to a
second base station, where the terminal is associated with RL ID
657. The long-term and short-term rules relating to these base
stations are in this example identical. This relationship with more
than one base station (sector, cell) for example refers to a
handover; fast hard-handover, soft-handover, or alike.
Regarding handovers, if the terminal moves to another new cell, the
base station knows that the terminal does not listen to the
AllocationTable in the old cell any more. The base station will
release this allocation rule commitment and will assign that space
for another terminal. If the handover happens between sectors of
the same base station, the base station may keep (hand over) also
the preferred commitment for a signalling occurrence in the
AllocationTable of the new serving cell. The allocation in the new
sector will not be guaranteed. Anyway, the RL_ID will change and
even SFN may change during the handover.
The allocation rules discussed above may be called active DRX rules
and/or active DTX rules and or active DTX/DRX rules. After the
traffic activity is over, there may still be another exponential
DRX rule to change from the active state to the idle state. The
idle state and active state DRX mechanisms may thus be different.
The Idle state DRX rules may follow a well-known exponential depth
sleep algorithm. The state transition between the active state
DTX/DRX and idle state DRX is described next.
The active state DTX/DRX occurs based on known or assumed
discontinuity, for example based on TTIs and on longer term
pointing capability. In the idle state DRX, exponential rules may
apply. As long as the DTX/DRX follows some traffic pattern or
discontinuity up to the longest supported TTI, say 40 ms or 80 ms
(or up to even 100 or 200 ms), active state DTX/DRX rules may be
applied. Also any pointing to the next continuum will keep the
terminal in the active state. If there is no activity within this
period of time, the UE enters the exponential sleep of the idle
state. In other words, the opportunity to receive paging is
arranged so that the UE will decode the AllocationTable after; 80
ms, 160 ms, 320 ms, 640 ms, 1280 ms, 2560 ms, 5120 ms (up to the
longest idle state DRX). So, exponentiality is applied in state
transition to the idle state.
FIGS. 9a, 9b and 9c relate to transition from the active state
DTX/DRX to the idle state DRX. FIG. 9a shows a state diagram, which
shows the idle state and active state, and possibly some other
states. The idle state DRX rules are different from the active
state DTX/DRX rules.
FIG. 9b is a state diagram for the active state allocation rules in
a communications device. In step 901, a session is set up or data
flows are activated. In step 902 it is checked whether the
communications device is in an idle state or in an active state. If
the communications device is in an active state, the DTX/DRX active
state allocation rules are updated in step 903 in accordance with
the new session or newly activated data flows. If the
communications device is in an idle state, it switched itself into
an active state in step 904 and creates active state DTX/DRX rules
in step 905. Thereafter the communications device repeats steps 906
to 912 until there is no data transmission for a predefined period
of time (step 913). In step 906, the communications device
determines whether it needs to follow a short-term allocation rule
(step 907) or a long-term allocation rule (908). The communications
device determines the length of the next DTX/DRX allocation period
after the current frame accordingly. In step 909, the
communications device monitors allocation information for
determining whether it needs to receive data in the current frame.
The communications device also determines whether it has a need to
transmit data and to indicate this need in step 909. In step 910,
the communications device encodes the payload to be transmitted
and/or decodes the payload allocated to it, if any. In step 911,
the communications device allows the rest of the duration of the
DTX/DRX allocation period to pass. The next activity in step 912
refers to data to transmit and/or receive in the next period of
DTX/DRX. If there is no activity during the longest addressable
active state DTX/DRX, the communications device switches to the
idle state in step 914. In step 915, the communications device
starts to apply idle state allocation rules. In step 916, if there
is no activity, the communications device has taken into use the
longest idle state period. When there is activity after step 914,
the communications device continues from step 901.
FIG. 9c is an illustration of possible triggers for allocation rule
updates or for DTX/DRX rule updates. These triggers may apply in
the base station for a given terminal or more commonly to more
terminals, or these triggers may apply in the terminal. Load
triggers are typically network originated, other triggers may be
network or terminal originated. The rules themselves will apply
equally in the base station for a given terminal and in the
terminal respectively.
It is appreciated that the term allocation information may refer to
a piece of information transmitted in connection with the set of
transmission resources whose allocation to communications devices
the allocation information specifies. As an example, consider an
allocation table in the beginning of a frame or a header in a data
packet/block. Allocation information may alternatively refer to a
piece of information transmitted separately from the transmission
resources whose allocation the allocation information specifies. As
an example, uplink allocation information is transmitted in the
downlink direction. Uplink allocation information may be
transmitted together with downlink allocation information.
It is appreciated that allocation information may be an allocation
table listing identifiers of communications devices and the
transmission resources allocated for the communications devices.
The allocation table may, but need not, list the transmission
resources allocated to the communications devices explicitly, or
use some coding system instead.
It is appreciated that the term communications device refers here
to any communications device capable of communicating via a
communications system. Examples of communications devices are user
equipment, terminals, mobile phones, mobile stations, personal
digital assistants, laptop computers and the like. Furthermore, a
communications device need not be a device directly used by human
users. Furthermore, a communications device may be a composition of
several devices.
It is appreciated that the term monitoring allocation information
refers to the functionality the communications device carries out
for being able to determine whether a specific piece of allocation
information indicates that this communications device is being
allocated transmission resources in the respective set of
transmission resources. Typically a communications device receives
symbols where the allocation information signalling bits are
carried in a channel coded format, and the communications device
decodes the channel coding of those symbols. Thereafter the
communications device interprets the meaning of the allocation
information signalling bits and behaves respectively. This is one
example of the functionality that the term monitoring intends to
cover. A more detailed example is given above in connection with
the second embodiment of the invention.
It is appreciated that the functionality to support embodiments of
the invention in the communications device and in the
communications system may be provided as hardware or a suitable
combination of software and hardware. It is appreciated that a
computer program in accordance with an embodiment of the invention
may be embodied on a record medium, and/or stored in a computer
memory.
It is appreciated that the features defined by the appended
dependent claims may be combined to form further combinations.
Although preferred embodiments of the apparatus and method
embodying the present invention have been illustrated in the
accompanying drawings and described in the foregoing detailed
description, it will be understood that the invention is not
limited to the embodiments disclosed, but is capable of numerous
rearrangements, modifications and substitutions without departing
from the spirit of the invention as set forth and defined by the
following claims.
* * * * *